The work done in this project has been an integral part of a team effort with NCI and NIAID laboratories to develop new inhibitors of HIV that target the highly conserved nucleocapsid protein (NCp7). The Bioorganic Chemistry Section has had the responsibility to design the actual drug candidates and to direct and participate in their synthesis. We reported last year on studies with a series of pyridinioalkanoyl thioesters (PATEs) and their ability to inactivate HIV-1 in an in vitro cytoprotection (XTT) assay. These findings were covered in a worldwide patent filing (PCT), and rights were licensed to our CRADA partner, Achillion Pharmaceuticals, Inc. of New Haven, CT. The CRADA was established in Dec., 2000. The mechanism of action of PATEs on recombinant NCp7 in vitro was shown to involve a transfer of the acyl group of the thioester to several cysteines in the NCp7 zinc finger domains (Basrur, et al., 2000). This past year we have carried out a vigorous program of synthesis of non-PATE (uncharged) 2-mercaptobenzamide thioesters in order to improve the oral bioavailability profile as predicted for drug-like molecules. In addition, we have explored a variety of chemotypes based on replacing the thioester bond with other potentially reactive acylating functions, most notably, thiolcarbamate and thiolcarbonate moieties. A US provisional patent was prepared, that covered these and further, related compounds, and was filed on Aug. 3, 2001. Many of these compounds are active against HIV-1, HIV-2 and SIV. Extensive in vitro and in vivo assays and tests have been performed including ones showing oral bioavailaility and antiviral activity against chronically and latently infected cells and infected PBMCs. Active compounds were equally active against laboratory strains of HIV-1, clinical isolates, and strains resistant to commonly used drugs. Manuscripts covering these findings are in preparation.